1. Field of the Invention
This invention relates to an apparatus and method for mixing fluids and is more particularly concerned with a piston operated mixer which receives fluids, for example air and propane gas, and combines them at a designated ratio. The mixer further allows the fluids to be mixed and delivered in amounts depending upon demand.
2. Description of the Prior Art
In the past, various systems have been employed for mixing air and propane gas for use as a replacement for natural gas. Such systems are described in Handbook Butane-Propane Gases, 4th Ed., 1962. One system uses mechanically interlocked, sliding valves which automatically open or close as demand increases or decreases, or which may be manually set. A blower or compressor draws the mixed gas from the mixing chamber and forces it through the distribution piping. The mixing apparatus, illustrated at page 267, employs a complex combination of diaphragms and piston to control flow. Other systems, similiarly described, include a venturi-mixer and an orifice meter ratio control system.
Such mixing systems are commercially available from Eclipse, Inc. and Selas Corporation of America. The Eclipse device includes two cones which control the air and propane gas quantities, respectively. This system includes a diaphragm which senses pressure imbalance and, in turn, activates a linkage that changes the respective orifice areas.
The Selas system also includes a diaphragm, which is attached to a non-rotatable piston. Gas pressure on the respective side of the diaphragm will cause the diaphragm to raise or lower, thus raising or lowering the piston and so controlling quantity of the delivered mixture. A rotatable "sleeve" surrounds the piston and can be set in various positions to accomplish a desired air/propane ratio.
Each of the above-referenced systems are more complicated and thus believed less reliable and efficient than my device.